Natura 2000 Areas, Road, Railway, Water, and Ecological Networks May Provide Pathways for Biological Invasion: A Country Scale Analysis

Invasive species are a major threat to biodiversity worldwide. Controlling their rapid spread can only be effective if we consider the geographical factors that influence their occurrence. For instance, roads, railway networks, green and blue infrastructure, and elements of ecological networks (e.g., ecological corridors) can facilitate the spread of invasive species. In our study, we mapped the occurrence of five invasive plant taxa (tree of heaven, common milkweed, Russian olive, black locust, and goldenrods) in Hungary, using field photos from the EUROSTAT Land Use and Coverage Area Frame Survey (LUCAS) database from the year 2015. Species point occurrence data were compared with the spatial characteristics of linear transport infrastructure and with the green and blue infrastructure. We found that the occurrence of tree of heaven and Russian olive was strongly related to the road and railway network. The average Euclidean distance of LUCAS points infected with these species from railway embankments and roads was much smaller than that of uninfected points. However, black locust and goldenrods were more common only along the road network. According to our results, the occurrence of some investigated invasive plants was over-represented in the HEN and within Natura 2000 areas of Hungary compared to non-infected points. Our results may provide important information for predicting the rate of invasion and for applying targeted management within the HEN, and Natura 2000 protected areas.

Ecological Networks and Fluvial Corridors in Calabria (Southern Italy)

The anthropic pressure on natural systems is the main cause for the present process of biodiversity loss in terrestrial biosphere [1]. Really, the human disturbance on Earth affects the 74.1% of terrestrial and marine habitats, including 22.4% completely modified, 51.7% partially disturbed and just the 25.9% in natural and pristine conditions [2]. At the beginning of third millenium, in the middle of a post-industrial era, named “Anthropocene” [3], mankind is causing the greatest mass extinction of wildlife in terrestrial biosphere [4-6].

Structuring Interaction Networks Between Epiphytic Bryophytes and Their Hosts in Yunnan, SW China

Ecological networks are commonly applied to depict general patterns of biotic interactions, which provide tools to understand the mechanism of community assembly. Commensal interactions between epiphytes and their hosts are a major component of species interactions in forest canopies; however, few studies have investigated species assemblage patterns and network structures of epiphyte–host interactions, particularly non-vascular epiphytes in different types of forest. To analyze the characteristics of network structures between epiphytes and their hosts, composition and distribution of epiphytic bryophytes were investigated from 138 host individuals using canopy cranes in a tropical lowland seasonal rain forest (TRF) and a subtropical montane moist evergreen broad-leaved forest (STF), in Southwest China. We structured binary networks between epiphytic bryophytes and their hosts in these two forests, which presented 329 interactions in the TRF and 545 interactions in the STF. Compared to TRF, the bryophyte–host plant networks were more nested but less modular in the STF. However, both forests generally exhibited a significantly nested structure with low levels of specialization and modularity. The relatively high nestedness may stabilize the ecological networks between epiphytic bryophytes and their hosts. Nevertheless, the low modularity in epiphyte–host networks could be attributed to the lack of co-evolutionary processes, and the low degree of specialization suggests that epiphytes are less likely to colonize specific host species. Vertical distribution of the bryophyte species showed structured modules in the tree basal and crown zones, probably attributing to the adaptation to microclimates within a host individual. This study highlights the nested structure of commensal interaction between epiphytic bryophytes and host trees, and provides a scientific basis to identify key host tree species for conservation and management of biodiversity in forest ecosystems.

Identification of ecological networks and nodes in Fujian province based on green and blue corridors

China's Green Space System Planning (GSSP) research has gradually expanded from central urban areas to municipal and provincial scales in recent years. Besides, the research on the role of green space in the water environment has also attracted much attention. However, the study of green corridors usually ignored hydrological data, which widespread absence especially in the large area scale. And the scale of green corridor construction mainly focused on central urban areas. This paper took China's Fujian province as an example. Based on the DEM elevation data, the article identified blue corridors without hydrological data. In addition, the green corridors were determined based on the land use data. According to the green corridors and blue corridors protection, we identified the ecological networks and nodes by the network analysis method. The results showed that the blue corridors identified by DEM data were consistent with the hydrological status quo. The regional status of the identified ecological networks and nodes were basically in line with their characteristics, proving the value of the planning methods. Finally, based on the identification results, suggestions for Fujian's ecological networks and nodes are put forward.

Plant community dynamics from the perspective of recruitment networks: introducing the Recruitment and Replacement model (R&R).

The study of plant community dynamics has a long tradition. However, this field has barely incorporated the tools developed in the modern study of ecological networks. Key for this incorporation is the availability of a theoretical model able to incorporate field data about plant-plant interactions. In this study I introduce the Recruitment and Replacement (R&R) model that explicitly incorporates empirical networks of plant-plant interactions that occur during recruitment. The R&R model is built on fundamental demographic rates and incorporates competition for space between adults, intra- and inter-specific effects of established plants on recruitment and the colonization of vacant space. The basic analysis of the model provides predictions regarding different aspects of plant community dynamics, like the environmental conditions and species properties under which facilitation of recruitment is more likely to occur, the effect of recruitment facilitation on invasion, the effects of plant-plant interactions on equilibrium abundances and community stability, and the network properties that should relate to species equilibrium abundances. Many of these predictions agree with findings from published meta-analyses, supporting the general validity of the recruitment networks framework as a general approach to integrate the study of plant community dynamics into the study of ecological networks.